P R O T O C O L
Open Access
Effects of cataract surgery and intra-ocular
lens implantation on visual function and
quality of life in age-related cataract
patients: a systematic review protocol
Shalu Jain
1*, Kavitha Rajshekar
1, Anjana Aggarwal
1, Akshay Chauhan
1and Vijay Kumar Gauba
1,2Abstract
Background:Cataract is the leading cause of blindness and low vision worldwide. Presently, cataract surgery is the only treatment for cataract and is very effective in restoring sight. In cataract surgery, the natural lens of the eye that becomes clouded is removed and replaced with an artificial intraocular lens. There are multiple techniques for removal of lens as well as many types of intraocular lenses available for implantation. For this reason, it becomes imperative to monitor the impact of different surgical techniques and different intraocular lenses on health-related quality of life (HRQoL) of the patients. This systematic review aims to evaluate HRQoL evidences on effects of different types of cataract surgeries and intraocular lenses on visual function and quality of life in age-related cataract patients.
Method:Databases like Cochrane, EMBASE, SCOPUS, NHS Economic Evaluation Database (NHS EED), Health
Technology Assessment (HTA) database, MEDLINE, ClinicalTrials.gov, Current Controlled Trials and World Health
Organization International Clinical Trials Registry Platform (WHO ICTRP) will be searched systematically. Two reviewers will independently screen studies using predefined inclusion and exclusion criteria along with the extraction of data, and assessment of methodological quality using a standard checklist.
Discussion: This systematic review will help in understanding how different types of cataract surgeries and intraocular lenses make a difference on quality of life of age-related cataract patients in terms of visual function and health-related quality of life. As the review attempts to bring together all the cataract-related HRQoL evidences pertaining to different cataract surgical techniques, different intraocular lenses and cataract-related complications, it will also identify gaps in evidence.
Systematic review registration: PROSPERO CRD42018092377
Keywords: Cataract, Health-related quality of life, Visual function, Health technology assessment, Economic evaluations, Cost effectiveness
© The Author(s). 2019Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
* Correspondence:shaluisjain@gmail.com
1Health Technology Assessment in India, Department of Health Research,
Ministry of Health and Family Welfare, Indian Red Cross Society Building, 1, Red Cross Road, New Delhi 110001, India
Background
Health Technology Assessment (HTA) is an internation-ally accepted tool to inform decision making for better management of existing resources for Universal Health Coverage (UHC) [1–3]. Health Technology Assessment in India (HTAIn) has been institutionalised in January 2017 under the Department of Health Research (DHR), Ministry of Health and Family Welfare (MoHFW) by the Government of India to facilitate the process of transparent and evidence-based decision-making for improved healthcare delivery [4]. HTAIn is entrusted with the responsibility to analyse evidences related to cost-effectiveness, clinical-effectiveness and equity issues regarding the deployment of health technologies like new medicines, devices and health programmes by means of HTA studies, which will in turn help in the ef-ficient use of a limited health budget and provide people access to quality healthcare at minimum costs [5,6].
The first HTA topic selected for study at HTAIn secre-tariat was‘Health Technology Assessment of intraocular lenses for treatment of age-related cataracts’. The re-quest for this topic came from Rashtriya Swasthya Bima Yojana (RSBY), a Government health insurance scheme that has now been subsumed by the National Health Protection Scheme (NHPS) under Ayushman Bharat Mission [7,8]. Under this HTA study, five individual lit-erature reviews were conducted to gather the evidences namely on clinical effectiveness, cost effectiveness, health-related quality of life (HRQoL), costing and equity. The present study (systematic literature review on HRQoL) is a part of the HTA study on‘Health Tech-nology Assessment of intraocular lenses for treatment of age-related cataracts’.
Cataract is a condition in which the lens of the eye becomes clouded preventing clear vision [9]. Cataract is the leading cause of blindness (51%) and low vision (33%) worldwide [10]. When vision < 20/200 in the better eye on presentation is defined as blindness, it has also been reported that cataract is responsible for 50– 80% of the bilaterally blind in the country [11–16].
Presently, cataract surgery is the only treatment for cataract, with high success rates, in restoring sight. The opaque lens of the eye is removed and replaced by an artificial intraocular lens [17, 18]. Cataract surgery as such is one of the most cost-ef-fective interventions though cost and clinical effectiveness of different surgical techniques and in-traocular lenses (IOLs) vary a lot [19]. In clinical de-cision-making, interventions are being primarily assessed based on efficacy and safety. However, it is also important to monitor the impact that treat-ments have on utility, i.e. health-related quality of life (HRQoL) using validated instruments [20, 21]. Utility is a measure of health preference anchored
around a value of ‘1’ for perfect health and ‘0’ for dead that is used in calculations of quality-adjusted life years (QALY) [22].
This systematic review aims to evaluate health-related quality of life evidences on effects of different cataract surgeries and intraocular lens implantation on visual function and quality of life in age-related cataract pa-tients. This review also attempts to bring together all the cataract-related HRQoL evidences pertaining to different cataract surgical techniques, different intraocular lenses and cataract-related complications.
Methods
This protocol has been registered a priori in PROSPERO (#CRD42018092377) [23] and follows the Preferred Report-ing Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines as included in Additional file1.
Review question
What are the changes in quality of life and visual func-tion in age-related cataract patients after undergoing a particular type of cataract surgery and intraocular lens implantation?
Search strategy and information sources
Strategies will be designed to identify all relevant studies for HRQoL among age-related cataract patients. We will search the bibliographic electronic databases like the Cochrane Library including the Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, SCOPUS, the NHS Economic Evaluation Database (NHS EED), Health Technology Assessment database, MEDLINE, ClinicalTrials.gov, Current Controlled Trials and World Health Organization International Clinical Trials Regis-try Platform (WHO ICTRP) systematically. For each database, we will use words and expressions from controlled vocabulary (MESH, EMTREE, and others) and free text searching. There will be no language or date restrictions for the literature search. Results will be managed using Covidence online software to facilitate automatic and manual removal of duplicate records, study screening and selection and record keeping. An example search strategy for EMBASE is given as Additional file2.
Criteria for considering studies for this review
The studies will be included based on the following criteria:
Inclusion criteria
Interventions: phacoemulsification, small-incision cataract surgery (SICS), extracapsular cataract extraction (ECCE), intracapsular cataract extraction (ICCE), rigid lens, foldable lens, monofocal lens, multifocal lens
Comparators: The comparators for the study would be as given below:
Surgery: ICCE, ECCE, SICS, phacoemulsification. Lenses: rigid IOL, foldable IOL, monofocal IOL,
multifocal IOL
Type of cataract: unilateral cataract, bilateral cataract
Outcomes: generic quality of life (QoL), HRQoL, vision-related quality of life (VRQoL), visual function (VF), cataract surgery-related complications
Study design: systematic reviews, meta-analysis, randomised controlled trials (RCTs), original observational studies, case-control studies, cohort studies, cost-effectiveness studies
Exclusion criteria
IOLs for non-age-related cataracts like congenital or paediatric cases
Studies reporting insufficient data for analysis Studies evaluating the association between QoL and
causes of visual impairment which are unrelated to cataract
Studies validating the test questionnaire or construct validation studies
Other eye disorders/diseases along with cataract Narrative review articles, study protocols, opinions,
abstracts
Year of publication and language
Eligibility will not be restricted by year nor by language of publication.
Inclusion screening process
Studies will be selected for inclusion through a two-stage process. The first stage will be to screen the literature search results (titles and, if present, abstracts) identified by the search strategy to identify all citations that poten-tially meet the inclusion/exclusion criteria detailed above. The second stage will be a‘preliminary’data ex-traction to aid in the study selection process. Full manu-scripts of selected citations that appeared potentially relevant will be obtained and preliminary data extraction will be done in order to ensure that all included studies have sufficient data pertaining to health-related generic
Table 1Preliminary data extraction table to be used for inclusion/exclusion of studies
Serial No.
Study ID
Title of study
Published in year
Study design
Patient population
Intervention
Comparator (If any)
Outcome measures (e.g. visual acuity, QoL, VF)
Instruments used
Included/excluded
Reason for exclusion
Table 2Data extraction table to be used for included studies Category (study is related to surgical techniques, intraocular lenses, surgical complications or any other aspect of cataract)
Study ID
Title of the study
Year of publication
Country where the work is done
Aim of the study
Study settings
Study design
Randomisation method (If RCTα)
Preference-based measures (generic/disease specific)
Which instrument is used
Sample size
Age criteria for patient recruitment
Patient recruitment details
Follow up details
Tariff details
Modelling details
Statistical tests used
Cost-effectiveness analysis (e.g, ICERβ, NHBγ)
Average age of patients
Visual function scores Pre-surgery Post-Surgery
Quality of life scores Pre-surgery Post-surgery
Results
Conclusion
Reviewer’s remarks
αRandomised Controlled trials,β- Incremental cost effectiveness ratio,γ- Net
Heath Benefit
quality of life and/or vision-related quality of life (Table1).
All studies will be assessed by two reviewers and checked independently by a third reviewer before taking a final decision. At each stage, any disagreements will be resolved by discussion.
Data extraction process
Two authors will extract data using a standardised data extraction form (Table 2) in Microsoft Excel, and the results will be compared for differences. Discrepancies in the extracted data will be resolved by discussion, with involvement of a third reviewer if necessary.
Critical appraisal strategy
The quality of included studies will be assessed by using a modified checklist recommended by Ara et al. [24] and insufficient detail in the primary studies will be noted under limitations. Three main criteria will be considered for quality assessment (Table 3). The fourth criteria from Ara et al. [24], which is ‘In line with reimbursement agency requirements’ will not be considered as the main aim of this study will be to systematically review cataract-related HRQoL evidences, and we do not intend to use the health state utility values (HSUVs) for a particular reim-bursement agency here. Two authors will apply the
criteria and it will be checked for differences with any disagreements resolved by consensus and involv-ing a third reviewer wherever necessary.
Method of data synthesis
Studies finally selected for inclusion in the review will be classified into different categories based on the type of cataract surgery and/or intraocular lens it involves and then each category will be classified into the subcategor-ies based on the type of QoL instrument used in the study. Data will be separately analysed for categories and subcategories accordingly.
We will pool the data for each category by per-forming a meta-analysis if we get enough studies with comparable outcome measures and with simi-larities in terms of study design, population, instru-ments used for measuring the health states, value sets used for assigning utility weights and reporting results. A fixed effects meta-analysis will be applied to obtain the pooled effect size with 95% confidence interval (CI) or else a random effects meta-analysis would be performed (heterogeneous, τ2 > 0). The heterogeneity level will be investigated by using I2 index. An I2 value of more than 75% will be consid-ered as an indication of significant heterogeneity. If there is evidence for substantial heterogeneity or inconsistency, we will not pool the results. In
Table 3Quality assessment checklist used for included studies (modified from Ara et al.) [24]
Criteria Consideration
Criteria 1. Relevance of the study
Relevant population How closely do the patient characteristics in the study match to the patient population we have described in our inclusion criteria (PICO)
Relevant health states Timing of data collection, e.g. pre-surgery, post-surgery, follow-up intervals. The use of any medications that is likely to have an independent effect on HSUVs (either detrimental or beneficial)
Criteria 2. Quality assessment
Sample size This was not considered as exclusion criteria, but the precision of the estimate was assessed
Response rates to the measure used
Are response rates reported and if so, are the rates likely to be a threat to the validity of the estimated HSUVs for the health states?
Loss to follow-up How large is the loss to follow-up and are these likely to threaten the validity of the estimates?
Missing data What are the levels of missing data and how are they dealt with? Are there details on the causes of the missing data?
Again, could this threaten the validity of the estimates?
Criteria 3. Utility values are measured and valued appropriately
Appropriate use of valuation method
If valuation methods are used (TTO, SG, DCE, VAS) they are used appropriately?
Does the valuation method provide preference based values anchored at 1 as equivalent to full health and 0 as equivalent to dead?
Are adequate details of the valuation method provided to allow judgement on appropriateness?
Appropriate use of GPMB Are adequate details of the PBM method provided (e.g. details given on the version used, the social tariff applied)
Was the GPBM delivered as intended? (e.g. wording and response options not changed)
Is the measure used for the group it was intended (e.g. is an adult GPBM being used for children? Is EQ-5D-Y used with the adult tariff?)
Appropriate health-state description (vignette)
circumstances where pooling of studies will be deemed inappropriate, we will only provide a quali-tative discussion of the findings with tables of find-ings and a narrative description.
Discussion
Literature search on cataract-related HRQoL evidences results in a huge number of studies when generic terms for HRQoL are used. Cataract-related studies reporting HRQoL are diverse in terms of study design, type of preference-based measure used (disease-specific or gen-eric measures) and type of instruments used (EQ 5D, Short Form 36, Visual Function Questionnaires like VF-11 and VFQ-14, etc.) as there is no set pattern for reporting HRQoL. The diversity of studies is seen as some compare HRQoL between different types of intra-ocular lenses (e.g. comparison between monofocal and multifocal lenses) where others compare it between different types of cataract surgical techniques (e.g. com-parison between phacoemulsification and small manual incision surgery). Still, others measure the HRQoL of cataract patients before and after surgery without men-tioning much the details of type of surgical technique and IOLs used. Against this backdrop, the current study will be a broad review to systematically explore, critically appraise and provide insight to the effects of different types of cataract surgeries and intraocular lens implanta-tions on visual function and quality of life in age-related cataract patients. If adequate evidence is available, this review may provide requisite data for decision modelling for economic evaluation studies. The review will also help in identifying gaps in availability of data that will help planning future modelling studies. As the review at-tempts to bring together all the cataract-related HRQoL evidences pertaining to different cataract surgical tech-niques, different intraocular lenses and cataract-related complications, it will also identify gaps in evidences and areas where future research is required.
Additional files
Additional file 1:PRISMA-P 2015 Checklist. (DOCX 30 kb)
Additional file 2:An example search strategy for EMBASE. (DOCX 19 kb)
Abbreviations
CDSR:Cochrane Database of Systematic Reviews; CENTRAL: Cochrane Central Register of Controlled Trials; DCE: Discrete Choice Experiment;
DHR: Department of Health Research; ECCE: Extracapsular cataract extraction; GPBM: Generic preference-based measures; HRQoL: Health-related quality of life; HSUV: Health state utility values; HTA: Health Technology Assessment; HTAIn: Health Technology Assessment in India; ICCE: Intracapsular cataract extraction; ICER: Incremental cost-effectiveness ratio; IOL: Intraocular lens; MESH: Medical Subject Headings; NHB: Net health benefit; NHPS: National Health Protection Scheme; NHS EED: National Health Service Economic Evaluation Database; PBM: Preference-based measures; PICO: Population, Intervention, Comparator, Outcome; QALY: Quality-adjusted life years; QoL: Quality of life; RCT: Randomised controlled trial; RSBY: Rashtriya
Swasthya Bima Yojana; SG: Standard gamble; SICS: Small-incision cataract surgery; TTO: Time trade-off; UHC: Universal Health Coverage; VAS: Visual analogue scale; VF: Visual function; VRQoL: Vision-related quality of life; WHO ICTRP: World Health Organization International Clinical Trials Registry Platform
Acknowledgements
This project is sponsored by the Department of Health Research and has an overall control of the design, conduct, analysis, interpretation and dissemination of the systematic review. The authors would like to thank Professor John E Brazier for helping with the data extraction form and critical appraisal methods. The authors would like to thank Dr. Nishant Jaiswal, Consultant, Evidence-Based Health Informatics, RRC North, Department of Telemedicine, PGIMER and Ms. Pranita Pradhan from ICMR Centre for Capacity building in Evidence-Based Medicine for North East Region, Department of Paediatrics, PGIMER, Chandigarh for helping in electronic searches of databases.
Authors’contributions
SJ is the guarantor of the review. SJ, AA, AC and KR were involved in the design of the protocol and systematic review. SJ conducted the scoping searches. SJ, AA and AC piloted the inclusion/exclusion form. SJ and AC piloted the data extraction form. AA will be the first reviewer, and AC will be the second reviewer for the systematic review. SJ drafted the manuscript. All authors read and approved the final manuscript.
Funding
None.
Availability of data and materials
Not applicable.
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
Author details
1Health Technology Assessment in India, Department of Health Research,
Ministry of Health and Family Welfare, Indian Red Cross Society Building, 1, Red Cross Road, New Delhi 110001, India.2Indian Council of Medical Research, (ICMR), New Delhi, India.
Received: 27 November 2018 Accepted: 22 July 2019
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